I’m a big fan of XP’s practice of spiking solutions. Although I’m not currently doing TDD because I barely know enough about iPhone development to make myself dangerous, I haven’t quite dropped all practices. I still use source control (just a local SVN repository) against the root of my spikes directory.
Here’s how I’ve been structuring myself:
The benefits of this let’s me quickly create new projects to learn a single lesson given the numerous tutorials out there, and then put that under source control for reference code at a later stage. I then spend some time integrating it into the MyPrototypeProject, making small incremental commits as I make progress. The best part is that if I make a mistake along the way, all I have to do is a svn revert -R . to get back to a working state if I get too frustrated or lost.